Combined FRP Reinforcement and Permanent Formwork for Concrete Members

Abstract

Results are presented from 12 beams tested to ultimate failure in four-point bending and having a fiber-reinforced plastic (FRP)-concrete construction of combined tensile reinforcement and permanent formwork. Specifications of the specimens were chosen to provide insight into the behavior of the novel construction approach under evaluation. The FRP pultruded section is a commercially available floor panel of nonstandard section, and as such it does not represent an optimum reinforcement solution. Salient results from the short-term experimental program are presented and discussed. Specific attention is given to the role of the interface between FRP and concrete in providing full composite action. A generalized analytical model for flexural behavior has been developed based on an iterative approach to allow for concrete cracking and real material constitutive laws. Analytical results are compared at serviceability and at ultimate limit state with those determined in the experiments and the agreement is generally found to be good. Reasons for the differences are discussed in the context of how the analytical method will be used in a rational fashion to find efficient and cost-effective hybrid members.